Bisphenol A (BPA): Does Our Everyday Environment Contribute to Disease?
On September 17, 2008, the Journal of the American Medical Association (JAMA) published the results of the first major epidemiologic study examining the health effects associated with the chemical bisphenol A (BPA). The study involved 1,455 adults aged 18 through 74. The authors of the study reported a significant relationship between urine concentrations of BPA and cardiovascular disease, type 2 diabetes, and liver-enzyme abnormalities. Those with the highest amount of BPA in their urine had nearly three times the risk of heart disease and more than twice the risk of diabetes as those with the lowest levels. And those with the highest BPA levels were still considerably below the level the FDA considers “safe.”
According to the National Institute of Environmental Health Sciences (NIEHS), the primary exposure to BPA is from our diet. BPA is a chemical used in the productions of plastics and epoxy resins. It can leach into our food and drink through items containing these materials, including: plastic water bottles, food storage containers, baby bottles, the protective internal coating of canned food containers, and polycarbonate tableware. It is also found in dental sealants and composites. Worldwide production of BPA has reached 7 billion pounds per year. Indeed, BPA is so widespread that a 2003-2004 survey conducted by the Centers for Disease Control (CDC) found detectable levels of BPA in 93% of 2,517 urine samples collected from people six years and older. It is even found in breast milk.
The safety of BPA is the subject of much controversy, and the recent JAMA article is the latest addition to the debate. Even governmental agencies have been in conflict over whether the chemical should be considered “safe” or not. In August, the Food and Drug Administration (FDA) published a draft report stating that typical BPA exposure levels from food and drink are safe. But the National Toxicology Program (NTP), an interagency governmental program, published a brief in which it found varying levels of concern regarding possible effects of BPA on the brain, behavior, and prostate gland in fetuses, infants, and children at current exposure levels, as well as its effects on early onset of puberty and reproductive effects. (The concern rating system and a discussion of their data is explained on the NIEHS website.)
The American Chemistry Council (which represents companies engaged in plastics manufacturing) maintains that BPA is toxic only at very high levels. Meanwhile, Wal-Mart, Toys R Us, and Babies R Us have said they will phase out baby bottles with BPA.
The BPA controversy has not been limited to the United States- it even extends internationally. Canadian regulatory agencies declared BPA a “toxic chemical” requiring aggressive action to limit human and environmental exposures. But the European Food Safety Authority said there is no risk to human fetuses or newborns because BPA exits the human body too quickly to pose a threat.
The potentially harmful effects of BPA were first discovered in 1998. Patricia Hunt, a geneticist, was conducting studies on mice in an effort to try to uncover causes of our widespread human reproductive problems. She realized that the janitor in her laboratory had used an abrasive cleaner that had scarred the plastic water bottles in the mice cages, which caused a single chemical to leak out- BPA. As a result, 40% of the mice in her control group had defects in their eggs.
Since then, dozens of scientists around the world have conducted studies linking BPA to harmful effects in rodents, including prostate and mammary cancer, genital defects, obesity, behavioral problems such as attention deficit hyperactivity disorder, and early onset of puberty. Skeptics, however, cite the inability to replicate the results of these studies as negating the evidence that BPA is harmful. But Hunt, along with 36 other researchers, published a paper in Reproductive Toxicology in 2007 in which they analyzed hundreds of studies conducted on BPA. They found that out of 128 government-funded studies, 91% concluded BPA was a health risk. On the other hand, out of the 12 industry-funded studies, none found BPA to be a health risk and failed to replicate the hundreds of other government studies to the contrary. Apparently, BPA is just another example of where science and politics (economics) meet.
Frederick S. vom Saal, who led the Reproductive Toxicology paper in 2007, also published an editorial article in this issue of the Journal of the American Medical Association (JAMA), commenting on the results of the recent epidemiological study. In his editorial, he faults the FDA for taking a toxicological approach to setting “safe” exposure levels, instead of using an endocrinological approach. According to vom Saal, the FDA based its acceptable daily intake dose (ADI) on “a concept first articulated in the 16th century: ‘The dose makes the poison.’” What is vom Saal referring to? A traditional toxicology approach operates on the premise that higher doses of any toxin will yield increasingly adverse physiological effects- in other words – more is worse. But when it comes to hormones or hormone mimicking substances, the opposite is true- higher doses can shut down the body’s response, while low doses are enough to cause effects. This approach is an endocrinological one. BPA is an estrogen-mimicking substance that does not act like a traditional toxin. Thus, vom Saal and others believe it has to be treated differently and examined under the endocrinological approach, instead of the toxicological one. Indeed, some recent studies have found that when BPA interacts with hormone receptors on cell membranes, concentrations as weak as one part per trillion can stimulate physiological effects. Vom Saal criticizes the FDA for taking a toxicological approach in setting safety levels of BPA, while ignoring “decades of published observations by endocrinologists.” He chides the FDA for ignoring recent findings from independent scientists and instead relying on outdated studies “predominately…funded by the chemical industry” in assessing safety.
So while the FDA has set our acceptable daily intake at 50 micrograms per kilogram of body weight, exposure levels much lower than that can actually be causing deleterious health effects. In Hunt’s research, she found BPA effects at just 20 micrograms per kilogram of body weight, making them one-half to one-third the FDA levels.
According to vom Saal, given the results of the most recent JAMA study, follow-up longitudinal studies on infants, children, and adolescents, as well as pregnant women and fetuses, are a “high priority.” Vom Saal cites the dramatic increase in childhood obesity and type 2 diabetes (which correspond with the exponential increase in BPA products over the last 30 years), as further correlating data pointing to the harmful effects of BPA.
Yet, despite the research conducted on BPA and the growing data showing that chemical pollutants and other carcinogens contribute to cancer and disease, there are still those who are adamant that our surrounding environment does not play a role in disease. Yet, in 2004, there were over 80,000 chemicals used in the United States, and less than 10% had been evaluated for safety, meaning that their effects on the immune, nervous, endocrine, and reproductive systems are unknown. (1)
The Center for Evaluation of Risks to Human Reproduction (CERHR) was established in 1998 to “assess the evidence that environmental chemicals, physical substances, or mixtures…cause adverse effects on reproduction and development and provide opinion on whether these substances are hazardous for humans.” The CERHR was born out of “widespread concern among health professionals, environmental scientists, and the public” that “environmental exposures may be contributing to human reproductive and developmental disorders.” According to the CERHR, between five and ten percent of couples desiring children encounter problems achieving pregnancy, approximately 35–50 percent of pregnancies are not successfully completed, and 3 to 5% of newborns have major birth defects.
Still, the majority of traditional medical practitioners do not address carcinogens and chemical pollutants in their treatment protocols. Nothing is done to try to rid the body of these substances. These are factors that are generally addressed only by “nontraditional” medical practitioners (albeit with varying degrees of sophistication, competency, and efficaciousness). In our clinical experience, reducing exposure to these substances and incorporating advanced treatments to eliminate toxins from the body has been critical to our patients’ ability to fight disease. Still, this approach is widely ridiculed. Websites such as the notorious “Quackwatch,” refer to “the irrational concept” that “modern life so fills us with poisons from polluted air and food additives that we need to be…detoxified.” In their opinion, those who examine and address toxicity as part of an approach to the treatment of disease are guilty of a “manipulative hoax.”
But as the data on the deleterious effects of BPA and other chemical pollutants continue to expand, and as the incidences of disease continue to grow, perhaps the skeptics will begin to listen. If we ever want to understand the underlying causes of disease, these factors cannot be ignored.
Resource Links:
JAMA Study on BPA and Editorial
Q&A and Tips to Reducing Your Exposure to BPA
NTP-CERHR Reports, Assessments, and Comments on BPA
Silent Spring Institute: Publications on Chemical Pollutants and Cancer
Scientific American BPA Article
Frederick vom Saal’s Website with References and Articles on BPA
Non-Internet Reference:
(1) Rapp, Doris J., M.D. Our Toxic World: A Wake Up Call. 2004. Environmental Medical Research Foundation, PO Box 60, Buffalo, New York 14223.
